B7200 wiring/regular issues

[Work Horse]

Hello again,

The hits just keep coming! The charge light hasn't shut off in days, and my fuel gauge quit working. Went through all wires, fuses, grounds, etc and I can't seem to narrow the issue down.

Yesterday I checked both Dynamo wires and found each wire was putting 20v+ to the regulator while running, and dropped to 11-12v with key on, engine off. Battery hasn't shown more than 12.3v regardless.

I'm questioning if the regulator can partially fail and that's why the battery isn't getting a full charge? I say partially because it does put out 12v to the fuel gauge with the key on via the Red wire. Which leads me to my next issue. I think I fried the fuel gauge. It was stuck on full for about a week, then I realized it had no ground. Touched the wrong terminal, blew a fuse, replaced and properly wired it up, and now it doesn't work at all. Verified there was voltage via Y/B wire to sending unit as well. Wanna say it was around 6v+ (I might be mixing up the voltage between the R, and Y/B wires) I believe I have it wired in correctly. Pics below. Thank you!!!

 

[Dave_eng]

Hello again,

The hits just keep coming! The charge light hasn't shut off in days, and my fuel gauge quit working. Went through all wires, fuses, grounds, etc and I can't seem to narrow the issue down.

Yesterday I checked both Dynamo wires and found each wire was putting 20v+ to the regulator while running, and dropped to 11-12v with key on, engine off. Battery hasn't shown more than 12.3v regardless.

I'm questioning if the regulator can partially fail and that's why the battery isn't getting a full charge? I say partially because it does put out 12v to the fuel gauge with the key on via the Red wire. Which leads me to my next issue. I think I fried the fuel gauge. It was stuck on full for about a week, then I realized it had no ground. Touched the wrong terminal, blew a fuse, replaced and properly wired it up, and now it doesn't work at all. Verified there was voltage via Y/B wire to sending unit as well. Wanna say it was around 6v+ (I might be mixing up the voltage between the R, and Y/B wires) I believe I have it wired in correctly. Pics below. Thank you!!!

Looking at your wiring has made me mark up one photo with questions.

Open the connector to the voltage regulator and see if any signs of over heating or melting on the terminals.

The rectifier can partially fail. The dynamo output is constant changing only with the engine rpm. The rectifier either send power to the battery or converts it to heat.

When you measured the dynamo leads were they disconnected? were you measuring AC voltage with your meter?

Which model of B7200. HST, D (w4WD manual)?

Dave

 

[Work Horse]

Open the connector to the voltage regulator and see if any signs of over heating or melting on the terminals.

When you measured the dynamo leads were they disconnected? were you measuring AC voltage with your meter?

Which model of B7200. HST, D (w4WD manual)?

Dave

Hey Dave,

Thanks for the response. I was out working the Kubota and just saw your message. I have a 7200HSTD.

I went and took the connector off and everything looks clean. I was going to see if I could pop the plastic off on the back side of regulator but it appears to be a solid molded unit.

I was not measuring AC, and the wires were connected - I just probed them. Went and measured AC while I was out there - I had roughly 25v with key on, and 42v with engine running. I'm assuming the regulator is shot - I found an aftermarket unit earlier and ordered it for $40.

Also ended up ordering a new fuel gauge and a flasher unit. Couldn't believe how much those both cost. Does my wiring look sound to the fuel gauge? I know colors are off and it looks like a rats nest. Just wanna get everything working before I make it all look neat. Thanks!

 

[Dave_eng]

Hey Dave,

Thanks for the response. I was out working the Kubota and just saw your message. I have a 7200HSTD.

I went and took the connector off and everything looks clean. I was going to see if I could pop the plastic off on the back side of regulator but it appears to be a solid molded unit.

I was not measuring AC, and the wires were connected - I just probed them. Went and measured AC while I was out there - I had roughly 25v with key on, and 42v with engine running. I'm assuming the regulator is shot - I found an aftermarket unit earlier and ordered it for $40.

Also ended up ordering a new fuel gauge and a flasher unit. Couldn't believe how much those both cost. Does my wiring look sound to the fuel gauge? I know colors are off and it looks like a rats nest. Just wanna get everything working before I make it all look neat. Thanks!

I am confused...... 25 volts with key ON. Was the engine running.... I hope it was. 42 volts at high rpm's is good.

The proper dynamo test confirms it is Ok.

Replacing the rectifier is wise,

To identify which half of the fuel level system is faulty, disconnect the non ground wire at the sending unit. Turn on the key. See if the fuel gauge needle moves. Next, ground the wire you disconnected and again see if the gauge moves.

The fuel gauge system relies on good grounds at the gauge and sender. The wiring diagram shows those grounds tied together and then grounded. Sharing a wire which is then grounded would be best on an old machine.

Dave

 

[Work Horse]

I am confused...... 25 volts with key ON. Was the engine running.... I hope it was. 42 volts at high rpm's is good.

Replacing the rectifier is wise,

To identify which half of the fuel level system is faulty, disconnect the non ground wire at the sending unit. Turn on the key. See if the fuel gauge needle moves. Next, ground the wire you disconnected and again see if the gauge moves.

It was 25v AC with key on, engine off. I recently had the engine running before testing voltage... And I'm using the most basic volt meter you could find. When I measured DC with engine off, key on, it was right at 12v. Does that sound correct? Is it no longer considered AC with the engine off?

I will check ground wires to sending unit/gauge and see what happens. Everything shares a common ground and I just redid all the ground wires under the dash. I tend to think I accidentally fried something, but I have no idea. Is there a way of knowing if one is bad? I know both units have power and ground, but gauge does not move at all.

 

[sdk1968]

key was on .. engine was OFF? & you got 25 volts?

i had a B7200HST that had all kinds of wiring issues & a rats nest of wires under the dash full of patches/splices...

nothing was the right color & so on. i went 1 wire at a time & replaced them ALL.

no clue which one was my real problem.. but that fixed it.

 

[Dave_eng]

your meter is highly susoect
It was 25v AC with key on, engine off. I recently had the engine running before testing voltage... And I'm using the most basic volt meter you could find. When I measured DC with engine off, key on, it was right at 12v. Does that sound correct? Is it no longer considered AC with the engine off?

I will check ground wires to sending unit/gauge and see what happens. Everything shares a common ground and I just redid all the ground wires under the dash. I tend to think I accidentally fried something, but I have no idea. Is there a way of knowing if one is bad? I know both units have power and ground, but gauge does not move at all.

The dynamo needs to be disconnected to be tested by measuring its AC voltage output while the engine is running first at idle and then max rpm's.

If you are measuring voltages when the dynamo is disconnected and not running then your meter is highly suspect,

Dave

 

[Work Horse]

key was on .. engine was OFF? & you got 25 volts?

i had a B7200HST that had all kinds of wiring issues & a rats nest of wires under the dash full of patches/splices...

nothing was the right color & so on. i went 1 wire at a time & replaced them ALL.

no clue which one was my real problem.. but that fixed it.

That's correct. AC-25vDC-12V

I have replaced all suspect areas, but it would be a lot more sound if I replaced all of them entirely. Wish they still made wiring harnesses at a decent price. It's nice to be able to use wiring diagram if needed. I ran out of black wire for ground as you may have noticed. What a mess!

 

[Work Horse]

The dynamo needs to be disconnected to be tested by measuring its AC voltage output while the engine is running first at idle and then max rpm's.

If you are measuring voltages when the dynamo is disconnected and not running then your meter is highly suspect,

Dave

Thanks again Dave. I will have to disconnect dynamo and try it again later. I told you I wasn't very good with wiring/electrical! And yes more than likely my meter is going to be off. It's an el cheapo and I really need to upgrade at some point. Thanks!

 

[Work Horse]

So.. just got home and did another test. This time I left the regulator off and probed the 2 pins from dynamo on the harness. Found I ran 15v (AC) at idle. And maxed out around 38v full throttle. (that $h!+ Was loud in my small "garage") What I didn't know was I would have to prove the two dynamo wires to get a reading. I assumed both lines provided power and I needed to have one grounded and test both wires. Total newbie I know.. with engine off, key on = 0v. Do these results sound good? I found that within my normal operating range I was doing 20-30v.

 

[Dave_eng]

So.. just got home and did another test. This time I left the regulator off and probed the 2 pins from dynamo on the harness. Found I ran 15v (AC) at idle. And maxed out around 38v full throttle. (that $h!+ Was loud in my small "garage") What I didn't know was I would have to prove the two dynamo wires to get a reading. I assumed both lines provided power and I needed to have one grounded and test both wires. Total newbie I know.. with engine off, key on = 0v. Do these results sound good? I found that within my normal operating range I was doing 20-30v.

Dynamo is OK.

You need new rectifier/regulator.

With the AC dynamo system there is no ground. A few older kubota's has 3 wires from the dynamo and again the voltage checks were between pairs of wires and never to ground.

Dave

 

[Work Horse]

Dynamo is OK.

You need new rectifier/regulator.

With the AC dynamo system there is no ground. A few older kubota's has 3 wires from the dynamo and again the voltage checks were between pairs of wires and never to ground. Thanks for all the help.

Dave

Awesome, glad to hear it. I've got all my ordered electronics coming this week and will let you know how it turns out.

 

[Work Horse]

Ok! Got the new regulator today, and problem solved! Battery is charging like normal. I also got a new flasher which works great. That cost almost $70 which is disgusting, but it's nice to get all the electrical working again...

Except for the fuel gauge. Brand New gauge/regulator and fresh wires/grounds and still no pulse. Pulled the sending unit out and I'm guessing it's junk. Had "rust barnicles" all over it. Guessing that's what I need.